42 Mark S. Davis and George W. Folkerts 



of developing eggs was occasionally observed. These eggs usually were 

 infested with fungi, which probably invaded after egg death rather than 

 having been the cause of mortality. 



Wood frog egg masses were easily recognized in breeding ponds by 

 their characteristic shape and the large size of their jelly envelopes. 

 Another distinguishing feature was a greenish color imparted to the jelly 

 envelopes by a unicellular green alga. Dickerson (1906) first noted the 

 presence of this alga and assumed that the relationship was mutualistic. 

 Gilbert (1942) also observed this alga in jelly envelopes of wood frog 

 eggs and identified it as Oophila amblystomatis, a species characteristi- 

 cally found in the egg jelly of Ambystoma maculatum. Surprisingly, 

 there has been little inquiry into the relationship between wood frog 

 eggs and algae by subsequent workers (see mentions by Pope 1964, Gatz 

 1973). Although the relationship between A. maculatum and Oophila 

 has generally been viewed as mutualistic (Gilbert 1942, 1944; Hutchin- 

 son and Hammen 1958; Hammen and Hutchinson 1962), a higher rate 

 of mortality has been related to the presence of the alga in some cases 

 (Anderson et al. 1971, Gatz 1973). Further investigation concerning the 

 relationship between the alga and R. sylvatica eggs is warranted. 



All egg predators observed during this study were invertebrates. 

 Mayfly naiads (Siphlonuridae, Ephemerellidae) and isopods (Asellidae) 

 were often present between adjacent egg envelopes within egg masses. 

 Caddisfly larvae (Phryganeidae) fed on the external surfaces of egg 

 masses, and one leech, Macrobdella decora, was found feeding on an 

 egg mass. Cory and Manion (1953) found this same leech destroying the 

 majority of wood frog eggs in some situations in Indiana, and thought 

 that its presence in certain populations of R. sylvatica might constitute a 

 check on population size. Since only one M. decora was observed dur- 

 ing our study, the effect of this species on Alabama wood frog popula- 

 tions is probably minimal. 



Hudson (1954) reported newts, Notophthalmus viridescens, feeding 

 on wood frog eggs in Pennsylvania. This salamander was a potential egg 

 predator in Alabama wood frog breeding ponds, but predation was 

 never observed during our study. The large diameters of egg jelly enve- 

 lopes of R. sylvatica in Alabama populations might reduce newt 

 predation. 



Hatching, Larval Development, and Larval Mortality 



The length of the period between egg deposition and hatching var- 

 ies directly with water temperature. Under field conditions, wood frog 

 tadpoles generally hatch in 7 to 9 days after eggs are deposited (water 

 temperatures variable, 5 to 17 °C). Larvae hatch at a fairly advanced 

 developmental stage, usually stage 20 (gill circulation, Gosner 1960) or 



